Describe the bug

I'm building a npm library in vite and import it in another vite project. When using

const worker = new Worker(new URL('./worker.ts', import.meta.url), { type: 'module' })

in the library, then the application fails to find the worker with an error in the web console similar to:

Loading Worker from “http://localhost:5173/node_modules/.vite/deps/assets/worker-C5kO0cPB.js” was blocked because of a disallowed MIME type (“”).

Because of the dependency optimization the library gets moved to .vite/deps, but the worker doesn't.

This happens because /* @vite-ignore */ gets added to the import URL when importing the worker via URL, which is correct for an application, but not for a library and especially when using relative paths.

Reproduction

https://github.com/RSWilli/vite-worker-import-bug-repro

Steps to reproduce

See the linked reproduction for more info.

1. cd application
2. npm run dev
3. open in browser, should see two messages from workers

System Info

System:
    OS: Linux 6.18 cpe:/o:nixos:nixos:26.05 26.05 (Yarara)
    CPU: (16) x64 AMD Ryzen AI 7 PRO 350 w/ Radeon 860M
    Memory: 16.06 GB / 30.53 GB
    Container: Yes
    Shell: 5.3.3 - /nix/store/hkbylipx1iiawqdcjv858p501wv81bpm-bash-interactive-5.3p3/bin/bash
  Binaries:
    Node: 24.12.0 - /nix/store/cikdc61gfwvdma6y0p9b5d5d448aqcv6-nodejs-24.12.0/bin/node
    npm: 11.6.2 - /nix/store/cikdc61gfwvdma6y0p9b5d5d448aqcv6-nodejs-24.12.0/bin/npm
  Browsers:
    Chromium: 143.0.7499.192
    Firefox: 146.0.1
    Firefox Developer Edition: 146.0.1

Used Package Manager

npm

Logs

No response

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• The provided reproduction is a minimal reproducible example of the bug.